Social media says your morning coffee spikes cortisol, drives fat gain and wrecks your hormones. But most of those claims come from studies using doses of 3 to 6 mg of caffeine per kilo, or up to 800 mg in one hit. In this round table, Dr Cliff Harvey sits down with HPI nutritionists Luke Gabites and Choong Kwan to look at what the research actually shows, and how they use coffee/caffiene with their own clients.

In this episode we cover:

• Why "coffee spikes cortisol" is a surface-level read of the research
• The doses used in caffeine studies versus a normal couple of cups
• Habituation: why regular coffee drinkers show little cortisol response
• Adrenaline, adenosine and what actually makes you feel alert
• Cortisol, "cortisol belly" and fat gain: what the evidence supports
• When caffeine is a real problem: high-stress clients, energy drinks and sleep
• Practical guidelines: timing, cups per day, double shots and green tea
• Coffee and iron absorption for plant-based eaters

Chapters

00:00 Intro and the team

01:41 Coffee, cortisol and the social media claims

03:37 Fat gain, hormones and crashes: the claims

04:17 Why a cortisol rise is partly the point

06:16 What the research doses really are

10:11 Dose in the real world: 800 mg is eight cups

11:55 Adrenaline first, cortisol later, and habituation

15:23 Athletes versus high-stress type A clients

19:06 Energy drinks, exercise and the rugby study

22:07 Half-life, timing and hidden calories in coffee

24:08 The latte client: does cortisol cause fat gain?

26:51 Cortisol belly and stress eating

30:05 The bigger stressors in people's lives

33:31 Individual responses and the holistic view

35:33 Practical caffeine guidelines

41:03 Green tea, L-theanine and iron absorption

42:22 Wrap-up and Nutripaedia

About the team

Dr Cliff Harvey is a clinical nutritionist, researcher and founder of the Holistic Performance Institute. Choong Kwan is a Registered Clinical Nutritionist, sports nutritionist and strength and conditioning coach based in Auckland. He helps time-poor parents and high performers build strong, healthy bodies without letting training and nutrition take over their lives. Find him at iamchoong.com. Luke Gabites is a Registered Clinical Nutritionist and Sports Nutritionist at Planted Nutrition in Auckland.

Mentioned in this episode

• Nutripaedia living review: Caffeine and Cortisol (HPI members) - https://holisticperformance.thinkific.com/courses/take/nutripaedia/audio/76943502-caffeine-cortisol
• Beaven et al. (2008), caffeine dose and cortisol in rugby league players: https://pubmed.ncbi.nlm.nih.gov/18458357/
• Dr Lauren Colenso-Semple on Instagram: https://www.instagram.com/drlaurencs1/
• Choong Kwan: https://www.iamchoong.com/
• Luke Gabites, Planted Nutrition: https://plantednutrition.nz

HPI links

• Roadmap: https://www.holisticperformance.institute/pages/roadmap
• Podcast page: https://www.holisticperformance.institute/pages/podcast
• Instagram: https://www.instagram.com/holisticperformancenutrition/
• Facebook: https://www.facebook.com/HolisticPerformanceNutrition/
• LinkedIn: https://nz.linkedin.com/company/holistic-performance-institute
• YouTube: https://www.youtube.com/@holisticperformance

Go further: want the full evidence on caffeine and cortisol, updated as new research lands? It's in Nutripaedia, our living evidence reviews for practitioners. Want to work in this space yourself? See the study pathways on the HPI Roadmap. If you got something from this episode, follow the show and leave a rating - it helps other practitioners find us.